Treating wood



Patented Dec. 27, 1932 UNITED STATES PATENT OFFICE PETER J. WIEZEVICH,OF ELIZABETH, NEW JERSEY, ASSIGNOB TO STANDARD OIL DEVELOPMENT COMPANY,A CORPORATION OF DELAWARE TREATING WOOD 1T0 Drawing.

This invention relates to an improvement in the treatment of wood,compressed fiber boards and the like, with mineral waxes wherebyresistance of the products to the ac- 5 tion of water is greatlyimproved.

The impregnation of wood with high melting waxes is now common practiceand the various features of this treatment have been described in thepatent and other literature.

Wood preferably after being thoroughly dried is immersed in a bath ofmolten high melting wax such as Montan wax with or without theapplication of pressure and a product of markedly superior propertiessuch as ease of polishing, resistance to warping, cracking, decay andthe like, is secured. Montan wax, which is especially suitable for thistreatment, is a mineral wax which is usually imported and is produced byextraction of lignite and pyropissite with suitable solvents. Otherwaxes such as carnauba and candelilla, hardened Montan wax' such asRomalin wax, or high melting parafiin waxes from petroleum, may be usedin place of the Montan wax. The wax may be used in admixture withsuitable solvents and penetrating oils such as cylinder oil, heavynaphtha and the like, an especially desirable composition being a heavyparaflin distillate from certain wax-containing petroleum crudes. Thisdistillate contains both wax and oil in suitable proportions for woodimpregnation. The wood may also be impregnated, either prior to or inconjunction with the wax or wax and oiltreatment, with fireproofingagents such as sodium biborate, paradichlorbenzine, and the like, andwith toxic agents or preservatives such as creosote, beta naphthol,sodium floride, zinc chloride, aluminum sulfate, arsenic compounds,borax and the like; These various agents may also be added to the woodprior to the wax treatment.

While the wax impregnated woods possess highly desirable properties theynevertheless generally possess the disadvantage that white blotchesappear on the surface of the wood wherever it has been allowed to comein contact with water for an appreciable length of time. For example,woods im- Application filed December 21, 1931. Serial No. 582,500.

pregnated with Montan or'high meltin petroleum waxes are very desirablefor 00ring because they do not warp and are easily maintained in ahighly polished. condition. However, white blotches appear onsuchflooring wherever water is spilt on it and these blotches can beremoved only by very vigorous polishing.

A method of rendering wax impregnated wood resistant to the action ofwater has been disclosed in co-pending application No. 57 0,974, filedOctober 24, 1931, by Charles W. Mudge. In this process the wood iscontacted with a diluted aqueous solution of an acidic treating agentwith or without the application of pressure prior to the waximpregnation treatment. With such processes involving a pretreatmentwith an aqueous solution it is generally preferable to dry the wood verythoroughly before subjecting it to 7 the wax impregnation treatment. Anobject of the present invention is to render the wax impregnated woodresistant to the bleaching action of water, by a treatment in which thewetting of the wood with water or aqueous solution is not required. Thewood may be subjected to the wax impregnation step either concurrentlywith or subsequent to this improved treating step.

I have now found that treating the wood with an acid gas such aschlorine, bromine, hydrogen'chloride, sulfur dioxide, or other acidicgases renders the wood after wax impregnation resistant to the action ofwater so that no spotting or bleaching occurs even when the wood iscontacted with water for I. long period of time or when water is spilledupon and allowed to evaporate from the surface of the wood underatmospheric conditions.

My invention will be understood from the following example which isillustrative of one method of operation:

Slabs of Southern yellow pine after thorough drying and planing areexposed for a 95 short period \of time, approximately one minute, togaseous chlorine at ordinary atmospheric temperature and pressure. Thewood is then impregnated in the ordinary manner with a high melting waxor a mixture of such wax in oil, with or without the application ofpressure. The wood after this treatment takes a high polish readily andshows no tendency towards spotting or bleaching when contacted withwater. The above treatment with gaseous chlorine may be conducted ifdesired directly on the freshly cut green wood or at any stage in thedrying proxess. 'ith highly reactive gases such as chlorine, bromine. orthe like. care must be taken not to expose the wood for too long a time.as otherwise discoloration or charring of the wood may result.I-lowever, a slight excess of the reagent produces a tinish that in someinstances may be desirable. For example, the wood maybe given an ebonyfinish by treatment with chlorine gas. The grain of the wood may alsobe. emphasized by careful treatment.

The acidic gas may be used in a highly concentrated or substantiallypure form. as described above. or it may be diluted with various inertgases such as nitrogen. methane, air and the like. The preferred timefor treatment will depend to some extent upon the nature of the wood.and upon the treating temperature, pressure. coneentratimi and type ofacidic gas used. and will be somewhat longer if a diluent gas is used.The use of elevated temperatures during the contacting of wood withacidic gas is not generally necessary but may be used if desired and thetime of treatment may be materially decreased thereby. Mixtures of theacidic gas and a diluent are especially preferred when it desired toconduct this step under pressure so that the wood may be thoroughlyimpregnated with the acidi agent. Such pressure treatment is especiallyadvantageous when this treating step is conducted before the wood is cutand planed to shape for the wax impregnation step, since the treatinggas then penetrates into the interior of the wood and subsequentoperations such as cutting, planing, etc. do not necessitate furtherpretreatment.

It is preferable to dry the wood thoroughly, cut and plane it to thedesired dimensions and then treat it with an acidic gas prior to the waximpregnation step. Under some conditions theacid gas treatment and thewax impregnation may becomhined. For example, in wax impregnation ofwood it is customary to subject the wood in sealed drums to pressurewith air and then to force the liquid wax-containing mixture. heated toa temperature insufiicient to char the wood. into the drum until thewood is completely immersed. The unabsorbed liquid is then withdrawn.and the pressure is released ,preferably after cooling the wood at leastbelow the melting point of the wax used, or of the treating mixture. Inthis treatment a small amount of acidic gas, say 1 to 5% may be added tothe air used and the wood is thereby thoroughly impregnated with thetreating agent and on completing the wax impregnation treatment showsthe same desirable characteristics. such as resistance to the bleachingaction of water, as already described. (are should also be taken inconducting this operation that the acidic gas is not permitted to reactwith the wood to too great an extent since such a treatment may cause amarked deterioration in both the. strength and color of the finishedproduct.

My invention is not to be limited to any theory of the operation of myprocess nor to any illustrative examples. but only by the followingclaims in which I wish to claim all novelty insofar as the prior artpermits.

I claim:

1. An improvement in the process of impregnating wood, fiber board andthe like with compositions in which Montan or a similar high melting waxis a major ingredient which comprises subjecting the wood to apretreating step comprising contact with an acidic gas.

2. An improvement in the process for impregnati'ng wood, fiber board andthe like with a high melting wax which comprises subjecting the wood toa pretreatment comprising contacting the wood with an acidic gas.

Process according to claim 2 in which the acidic gas is hydrogenchloride.

4. Process according to claim 2 in which the acidic gas is chlorine.

Process according to claim 2 in which the acidic gas is diluted with aninert gas.

6. Process according to claim 2 in which the pretreatment is conductedwith a gaseous mixture of an acidic compound and an inert gas atsuperatmospheric pressure.

7. An improved process for impregnating wood with high melting waxcompris ing subjecting the wood to contact with a mixture of hydrogenchloride and air at an elevated pressure. immersing the wood while undersuch pressure in a bath comprising a molten high melting wax at atemperature insuflicicnt to char the Wood, withdrawing the unabsorbedmolten wax, cooling the wood and subsequently releasing the pressure.

PETER J. WIEZEVICH.

